This invention relates to a mattress having a core which is completely encased in resilient foam insulation.
In conventional mattress construction, a mattress core such as a metal innerspring unit—usually having an array of parallel coil springs surrounded top and bottom by respective border wires which define the edges of the mattress—is covered with padding and fabric. The word “fabric”, as used herein, means any flexible material made of yarns or fibers, including woven materials, knit materials, and non-woven materials such as spun-bond material and the like made from bonded or interlocked fibers. The yarns or fibers may be natural or synthetic. Non-fibrous padding, which often is a polymeric foam, is commonly called “insulation”.
Some of the insulation is usually secured to the border wires, or to the coil springs, by metal connectors such as hog rings which are passed through the material and crimped around the underlying metal component. Other insulation layers may be attached at least temporarily by the adhesives. The insulation layers are ultimately covered and secured in place by a fabric material which conceals the other components and presents a finished appearance.
Traditional mattresses are symmetrical (same top and bottom) and are expected to be inverted occasionally to distribute wear and tear and maximize comfort. Another type of mattress, which has recently gained popularity, is the so-called “one-sided” mattress. A one-sided mattress is intended not to be turned and in fact has only one comfortable side on which one can sleep. The other side may have a fabric, or thinly padded, covering. The one-sided mattress is an advantage for customers who prefer not to turn mattresses.
Most mattresses are not thickly padded at the sides. This can result in a harsh-feeling edge near where the border wires pass. Some prior inventors have proposed constructing a foam “tray” or envelope to contain the innerspring. An advantage of thick insulation is that it looks better when upholstered, and is capable of providing good vertical support. However, placing thick foam at the upper edges of the mattress can produce edges which are perceived as weak or unstable when sat upon.